While significant progress has been made in the range of 0.5-2 terahertz integrated circuit fabrication, the measurement infrastructure for characterizing such components remains largely undeveloped. Currently, individual devices must be diced, or separated by other means, and mounted to a fixture for measurement. Further, for commercial probes that are currently available up to 340 GHz, their associated manufacturing techniques would not be transferable for higher frequency designs.
Probe structures that interface with integrated circuits exist commercially up to 500 GHz, but are very expensive since they typically rely on hand assembly of several components. At higher frequencies hand assembly becomes increasingly difficult to the point where a different approach is necessary. Moreover, even at 500 GHz and lower, for instance, it is a difficult assembly and yields a fragile product.
The conventional means of using fixtures for calibrated measurements of integrated circuits is extremely time-consuming and expensive (e.g., both in having to make the fixture and then assemble the device into the fixture and then make the measurement). By mounting a device in a fixture, additional “parasitic” effects are created that can mask the true response of the device itself. De-embedding the device response from the effects of the fixture is often difficult. It is preferable to measure the bare device on wafer prior to dicing and mounting. Moreover, a variety of calibration techniques have been developed to remove measurement errors due to probes and allow direct on-wafer measurements. Applying this to a fixtured device is difficult if not impossible.
Accordingly, there is a need in the art for direct on-wafer probing that allows rapid prototyping and characterization and also eliminates parasitic effects and responses associated with fixtures
Accordingly, there is a need in the art for calibrated on-wafer measurements of submillimeter-wave devices (about 300 GHz to about 3,000 GHz) and Terahertz devices (about 100 GHz to about 10,000 GHz), which in turn would significantly reduce the effort and cost required to characterize a wafer of devices while increasing the accuracy of the measurement by eliminating errors and effects associated with the fixture.
Moreover, there is a need in the art for improved manufacturing and reliability of probe structures pertaining to millimeter-wave devices (about 30 GHz to about 300 GHz).